With any luck, you won't need this phrase too often. Have you ever spotted an Italian 'making horns'?  Here's a demonstration in case you're not sure what that looks like: No, they're not telling you to 'rock on'. In Italy the gesture is a sign you're hoping for good luck, similar to crossing your ngers in English-speaking countries.

Le corna ('horns') invoke bull-like strength and they're thought to ward off il malocchio or 'evil eye' – any kind of curse or ill fortune. (Note that one horn, il corno, is masculine, but the plural mysteriously becomes feminine and ends unusually in ~a.)